Ralph Fiennes plays a hedonistic music producer (holding up one of his triumphs: t|Fox Searchlight

Ralph Fiennes can play introspective, but he’s just as masterful when he’s the opposite. You can see the outgoing, sometimes maniacal side of Fiennes in film like “In Bruges” and “The Grand Budapest Hotel.” And you can see it in “A Bigger Splash,” the latest from “I Am Love” filmmaker Luca Guadagnino.

Fiennes plays Harry, a legendary music producer who’s never entered his chill middle-age period. This enrages an old flame, Tilda Swinton’s rock star Marianne Lane, who’s trying to enjoy a quiet vacation — after a vocal cord surgery that has rendered her mostly mute — on the Italian island of Pantelleria with her boyfriend (Matthias Schoenaerts). Then Harry shows up, and with his newly discovered young daughter (Dakota Johnson).

Harry’s more thoughtful than he lets on: “He’s not always going crazy,” Fiennes says. “There are moments when he’s watching people. He’s quite observant. He’s quite sensitive, actually. He sees everyone. For all his noise and verbosity, he sees people. He picks up on people quite quickly.”

He’s also great at his job: “I’ve always felt he’s a very good producer, despite all the party animal antics you see. He’s really good at putting music together and guiding musical artists,” he explains. Fiennes didn’t have to go far for research: His brother Magnus is a seasoned pro in the music business. “My brother is a great producer. Socially, he’s very engaging and fun, but actually he’s very focused in his work. He’s very meticulous.”

Harry’s deep bond with Marianne: “The way I imagined his history with Marianne was that a lot of her best recordings and work were formed by Harry. That underpinned their relationship. I think she was at her best as a gifted performer and singer when he helped shape her.

"But he couldn’t stop his hedonistic lifestyle and went off the rails. She couldn’t handle it,” Fiennes says. “Whatever happened, she’s had enough. She has walked away … and found a new life for herself with Paul. And Harry doesn’t like that. Even though he’s been responsible for a large part of wrecking their relationship. Human beings, we go in these circular patterns. It all feels horribly familiar.”

A prisoner of his own freedom: “It’s in Harry’s nature that if he sees a young girl who’s a back-up singer, he chases her,” explains Fiennes. “He’s a man who gives himself permission always to take what he wants. He’s in that sense selfish, I suppose. But he’s existentially very free. He probably told himself he didn’t want to be hemmed in by the obligations or the compromises of relationships. Now he’s realizing he’s lost something.”

Acting alongside a largely mute Swinton: In the script Fiennes signed up for, Marianne actually did talk. Then suddenly she didn’t. “Initially, I was a bit cautious. I worried that it would take something away from Tilda. Your dialogue is your ammunition,” he recalls.

But he wound up liking it. “It gives an odd color to the film —in the good sense of ‘odd.’ If it had just been dialogue, old lovers going back and forth, we would probably fall into all sorts of slightly cliched areas —someone saying ‘I don’t want you, this is my new life.’ There was a bit of that in there, but it’s in the context of her not being able to speak, and probably her not wanting to. I have to say, with hindsight, once we started filming I thought, ‘This is working.’”

Harry’s relationship with Penelope, his daughter: “He loves how cool she is, how independent. He’s intrigued by her. Harry’s the sort of guy who will feel someone’s energy quite quickly, and he’s learned to not be over-attentive to Penelope,” he says.

“He sees her as a sexual young creature, and part of him is intrigued by that. But I don’t think he’s trying to sleep with her or anything like that. He’s learning who she is, this new creature that is his daughter," he explains. "He’s never experienced her as a child or as a baby. I would imagine that’s quite a weird one, if someone says, ‘Here’s your daughter as the result of a fling from long ago,’ and this potent young woman enters the room. It’s probably a bit of a mindf—. I think Harry’s dealing with it quite well.”

More about Penelope: “Some teenagers can see adult bulls—. She sees his bulls—, but —and I can’t speak for Dakota — I don’t think she was repulsed by Harry,” Fiennes says. “She strikes me, as some young teenagers are, very canny about adult behavior. They see stuff, and I think she’s like that. She sees all the pretenses and the posturing of adults. She’s a very cool character, actually.”